Effects of Cannabis on the Adolescent Brain

Summary & key facts

This paper looked over brain-scan studies, thinking tests, and animal research about cannabis use in teenagers. It found that teens who use marijuana heavily often show weaker thinking skills, and differences in brain size, structure, and activity. But the studies do not prove that cannabis caused those differences. The authors say we need long-term studies that follow kids over time to tell if cannabis itself changes the developing brain, how much use matters, and how cannabis interacts with other drugs like alcohol.

Key facts:

• The review combined results from brain imaging, cognitive tests, and animal studies about cannabis and the adolescent brain.
• Marijuana is the second most widely used intoxicant among teenagers.
• Teens who use marijuana heavily often show worse performance on thinking and memory tests.
• Heavy teen marijuana use is linked with changes in brain structure and brain activity.
• It is not clear whether those thinking and brain differences come from cannabis use or from pre-existing differences that made some teens more likely to use cannabis.
• The authors recommend long-term studies that follow young people over time to separate effects of dose from pre-existing differences and to study interactions with other drugs such as alcohol.

Abstract

This article reviews neuroimaging, neurocognitive, and preclinical findings on the effects of cannabis on the adolescent brain. Marijuana is the second most widely used intoxicant in adolescence, and teens who engage in heavy marijuana use often show disadvantages in neurocognitive performance, macrostructural and microstructural brain development, and alterations in brain functioning. It remains unclear whether such disadvantages reflect pre-existing differences that lead to increased substances use and further changes in brain architecture and behavioral outcomes. Future work should focus on prospective investigations to help disentangle dose-dependent effects from pre-existing effects, and to better understand the interactive relationships with other commonly abused substances (e.g., alcohol) to better understand the role of regular cannabis use on neurodevelopmental trajectories.

Topics

Cannabis and Cannabinoid Research Neuroscience and Neuropharmacology Research Prenatal Substance Exposure Effects

Categories

Health Sciences Medicine Pharmacology

Tags

Brain development Cannabidiol Cannabis Clinical psychology Cognition Developmental psychology Effects of cannabis Medicine Neurocognitive Neuroimaging Neuroscience Psychiatry Psychology

Substances

Cannabis

Conditions & symptoms

Substance abuse disorder Difficulty focusing Lack of energy or motivation